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Dust transport to the tropical/subtropical northwestern Pacific over the past 600 kyr was investigated using radiogenic isotopes ( 87 Sr/ 86 Sr and ε Nd ), together with the clay mineral composition, of eolian dust preserved in a sediment core obtained from the Philippine Sea (12°30′N, 134°60′E). These data revealed the influence of two prevailing dust sources, namely, the Asian deserts and nearby volcanic arcs (e.g., the Luzon Arc), with average contributions of around 70% and 30%, respectively, from each. The clay mineral composition of the core resembled dust from the central Asian deserts (CADs; e.g., the Taklimakan Desert) as in the north-central Pacific, but published aerosol data collected near the study site during winter/spring have the mineralogical signature of dust originating from the East Asian deserts (EADs). These data indicate that the relative contribution of EAD dust increases with the northeasterly surface winds associated with the East Asian Winter Monsoon (EAWM) during winter/spring, but the Prevailing Westerlies and Trade Winds that carry dust from the CADs is the dominant transport agent in the overall dust budget of the study site. The results of this study contradict the prevailing view that direct dust transport by the EAWM winds in spring dominates the annual flux of eolian dust in the northwest Pacific.

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The weathering conditions, provenance, and tectonic setting of shales from the Pimienta (PF; upper Jurassic), Huayacocotla (HF; lower Jurassic), and Méndez Formations (MF; upper Cretaceous) of the Molango Region, Hidalgo, Mexico have been studied for the first time using mineralogy, major, and trace element data. The X-ray diffraction (XRD) data reveals that the shales consist mostly of illite and muscovite clay minerals. The SEM-EDS study indicates that the PF and HF shales are rich in phosphate minerals and MF shales are abundant in zircon mineral. The chemical index of alteration (CIA  59 to 93) and their position in the A-CN-K (Al 2 O 3-CaO + Na 2 O-K 2 O) ternary diagram point to moderate to intense weathering in the source region. The La/Sc, Th/Sc, and La/Co ratios are more enriched and the Cr/Th and Eu/Eu * ratios are more depleted in MF shales than in the PF and HF shales, indicating derivation from a more felsic source than the PF and HF shales. Similarly, the average Zr content in MF shales (475 ± 185) is higher than in PF (133.9 ± 9.3) and HF shales (139.6 ± 18.2), which suggests a more enriched concentration of zircon mineral among the MF than the other shales (F calc = 32.9820669 and (F crit) 99% = 6.48949, where F calc > (F crit) 99% indicates that data populations are significantly different at 99% confidence level). The LREE enrichment, flat HREE, and negative Eu anomalies in chondrite-normalized plots are attributed to felsic source rock characteristics for the three groups of shales. The trace element concentrations point to an extensional setting (passive margin) for the Jurassic shales (PF and HF) and an active margin setting for the Cretaceous shales (MF).

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